GSH-Responsive PBAE Polymers for IL-12 mRNA Delivery in Melanoma Immunotherapy

Melanoma is a highly aggressive cancer with significant treatment challenges due to its immunosuppressive tumor microenvironment. Among its subtypes, uveal melanoma (UM), as a distinct subtype arising in the immune-privileged ocular site, currently lacks effective therapies to improve overall survival.

We developed a glutathione (GSH)-responsive poly(β-amino ester) (PBAE) platform for intracellular IL-12 mRNA delivery. By optimizing the ratio of GSH-responsive diacrylate monomers and amine structures, we synthesized and screened a library of candidate polymers for transfection efficiency. Nanoparticle size, stability, GSH-triggered disassembly, and mRNA release were characterized. Cellular uptake, protein expression, endo/lysosomal escape, cytotoxicity, and systemic safety were assessed in vitro and in vivo. Efficacy was evaluated in subcutaneous, intraocular, and lung metastasis mouse models using the B16F10 melanoma cell line.

The optimized polymer PSS0.5-A2B2 formed stable mRNA-loaded nanoparticles (approximately 100 nm) and exhibited time-dependent disassembly under GSH-rich conditions, enabling efficient mRNA release and enhanced IL-12 expression. In vitro, it enhanced cellular uptake, IL-12 expression, and endo/lysosomal escape. In vivo, no significant systemic toxicity was observed. IL-12 mRNA delivery significantly suppressed tumor growth, promoted apoptosis, and reduced metastasis. Combined intravitreal and intravenous administration showed superior antitumor efficacy.

This GSH-responsive PBAE platform enables biocompatible intracellular IL-12 mRNA delivery, offering a promising local-systemic combinatorial immunotherapy strategy for melanoma, holding potential promise for UM.